The hypothetical surface of the earth that coincides everywhere with mean sea level.
The hypothetical surface of the Earth that coincides everywhere with mean sea level and is perpendicular, at every point, to the direction of gravity. The geoid is used as a reference surface for astronomical measurements and for the accurate measurement of elevations on the Earth's surface.
In geodesy, the earth viewed as a hypothetical ellipsoid with the surface represented as a mean sea level.
German from Greek geoeidēsearthlikegēearth-oeidēs-oid
American Heritage Dictionary of the English Language, 5th Edition
Geoid Sentence Examples
The inequalities of the geoid in no case exceed 300 ft.
Granting that the geoid or mean surface of the ocean is a uniform spheroid, the distribution of land and water approximately indicates a division of the surface of the globe into two areas, one of elevation and one of depression.
Hence the geoid or figure of the sea-surface is not part of an ellipsoid of rotation but is irregular.